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Dangerous Insects, Safe Repellents


"When insects take over the world, quips the comic Bill Vaughan, "we hope they will remember with gratitude how we took them along on all our picnics.

“When insects take over the world,” quips the comic Bill Vaughan, “we hope they will remember with gratitude how we took them along on all our picnics.”

While bugs at picnics have long been the topic of bad jokes, what once was a mere irritation is now a major health risk.

Insect-borne disease is a leading cause of sickness and death worldwide. Mosquitoes alone transmit disease to more than 700 million persons annually. Malaria kills three million people each year, including one child every 30 seconds. Although insect-transmitted infections are currently a much greater health problem in tropical and subtropical climates, no part of the world is immune. In Canada and the US, arboviruses transmitted by mosquitoes cause sporadic outbreaks of eastern equine encephalitis, western equine encephalitis, St. Louis encephalitis and La Crosse encephalitis. In 1999, the West Nile virus, transmitted by mosquitoes, was detected for the first time in the Western Hemisphere.

Traditional Repellents and Brain Damage

At the same time, traditional DEET-based (N,N-diethyl-3-methylbenzamide) chemical insect repellents are themselves repelling health conscious consumers because of their proven toxicity. In 2003, a Duke University Medical Center pharmacologist recommended caution when using the insecticide DEET after his studies on rats found that DEET causes diffuse brain cell death and behavioural changes after frequent and prolonged use.

While DEET’s level of toxicity is still being intensely debated, the pharmacologist, Mohamed Abou-Donia, PhD, says that his 30 years of research on pesticides’ brain effects clearly indicate the need for caution among the general public. His numerous studies on rats demonstrate that frequent and prolonged applications of DEET cause neurons to die in regions of the brain that control muscle movement, learning, memory, and concentration. (The complete report can be found online at

Although studies continue to show that DEET-based products can be depended on for longer-lasting effects when compared to natural repellents, frequent application of natural repellents is a small price to pay to avoid brain damage. And DEET is not the perfect repellent by other measures, either; it can be washed off by perspiration and rain, and its efficacy plummets with rising temperatures. DEET does kill bugs, but it’s also capable of dissolving watch crystals, the frames of glasses, and certain synthetic fabrics.

So, how does a health conscious consumer protect his or her family from voracious and potentially deadly bugs? Certain essential oils have proven to be highly effective in combating mosquitoes, ticks, and other irritating and hazardous insects.

Essential Oils, Effective and Safe

Julia Lawless, in her excellent book The Illustrated Encyclopedia of Essential Oils (Element Books, 1995), recommends the following essential oils for fending off mosquitoes, ticks, fleas, and other insect pests: geranium (actually rose geranium), lavender, citronella, eucalyptus, Atlas cedarwood, and clove.

While you’ll often see citronella in natural repellents (sometimes it is the only ingredient) it isn’t the most effective of the oils. It’s frequently used because it’s inexpensive. A 2003 study at Guelph University found that while citronella was 30-per-cent effective in repelling mosquitoes, rose geranium oil was 97-per-cent effective. (See the university’s website, Rose geranium oil is rarely used in commercial natural insect repellents simply because it is very expensive. So, when shopping for a natural insect repellent, seek one containing the above essential oils, but make sure that rose geranium (or simply geranium) essential oil is one of the ingredients.


Just because a product is labelled “natural” doesn’t mean you can carelessly slather it on. Some precautions apply:

  • Keep natural repellents out of eyes and mouths.
  • Don’t apply repellents to children’s hands since children sometimes stick their fingers in their mouths.
  • Don’t apply over cuts or wounds.
  • Apply only to exposed skin and clothing.
  • Don’t use sprays directly on face. Spray first on hands.
  • Follow the instructions on the package.

Most natural repellents rely on fragrance for their deterrent effect, so remember to apply frequently.

You and your loved ones will be safer, healthier and, as an extra bonus, you’ll all smell great.



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